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...without the hysteriaSun, 02 Aug 2015 22:23:29 +0000en-UShourly1http://wordpress.org/?v=4.2.3What happened to the legendary great white shark, Cal Ripfin?http://www.thedorsalfin.com/editorial/what-happened-to-the-legendary-great-white-shark-cal-ripfin/
http://www.thedorsalfin.com/editorial/what-happened-to-the-legendary-great-white-shark-cal-ripfin/#commentsSun, 02 Aug 2015 22:23:29 +0000http://www.thedorsalfin.com/?p=6437Now, that August has arrived it’s about that time of year when great white sharks (Carcharodon carcharias) begin to arrive at Mexico’s Isla de Guadalupe Biosphere Reserve. The island is regarded as one of the best places on Earth to view white sharks in their natural habitat. However, it’s one shark in particular that many are holding out hopes to see return.
Cal Ripfin (aka Shredder) was one of the most well-known great white sharks at Guadalupe prior to his disappearance following the 2011 season.

From 2001 to 2011, Cal Ripfin (aka Shredder) was one of the most well-known great white sharks to visit Mexico’s Isla de Guadalupe. Easily recognized by an injury to his dorsal fin that occurred sometime between the 2004 and 2005 season, Cal was a “fan favorite” of divers and photographers due to his inquisitive and curious nature. He would often swim right up the cameras as if he was posing for a photo opportunity.

White sharks gather at Guadalupe in the later months of the year, with the prime season considered to be between August and November. Cal consistently visited Guadalupe every season for 10 years straight, and his arrival was generally quite predictable. In 2009, he was absent early on in the season, which caused a bit of concern among researchers and divers, but he eventually showed up about midway through the season. However, after failing to be seen during the 2012 season, concerns once again rose for the well-being of Guadalupe’s favorite shark. When 2013 and 2014 passed by without any sighting of Cal Ripfin, hopes of his return were dampened even further.

Cal Ripfin (aka Shredder) wasn’t shy about swimming right up to the camera, which often created great opportunities for close-up shots.

While migratory tracking data is limited among Guadalupe white sharks, the available data indicates that SPOT tagged males follow a somewhat predictable pattern each year. The data shows males traveling to Guadalupe in the latter half of a year, and spending the rest of their time in the Shared Offshore Foraging Area (SOFA) (aka “the White Shark Cafe”), a remote area in the mid-Pacific. If the tracking data available is representative of the migratory behavior of all male Guadalupe white sharks, it does not bode well for Cal Ripfin, since it’s very likely that he would have been seen at Guadalupe over the past 3 years had he returned.

The question of why this male great white shark suddenly stopped returning to Guadalupe is one that will likely go unanswered, unfortunately.

So, what could have happened to him? Did he change his migratory routine? Did he die of natural causes, fall prey to another predator, or end up in a fishing net? At this point, it seems likely that his fate will always remain a mystery. Somewhere, I still have a tiny glimmer of hope that he’s still out there, but each year that glimmer gets a little more faint.

A video shot off Gansbaii, South Africa of a white shark bumping a cage, after charging a hang bait, has been making the rounds in the (largely tabloid) media today. Some of the more creative news outlets have referred to the shark in the video as “trying to bite through steel bars of diving cage” and “charging the cameraman.” However, the behavior seen in the video does not appear to document anything beyond the shark going after a bait in close proximity to the cage and then bumping the cage after the bait was pulled away. The white shark does get briefly “tangled” with the bars of the cage, but eventually swims off without further incident.

White sharks do not have the ability to swim backwards, so when they are charging a bait momentum will often cause them to continue in the same direction, even if the bait is pulled away from them. Additionally, when attempting to bite prey, white sharks will often roll their eyes backward as a protective measure, rendering them temporarily blind, which can also contribute to collisions if bait is close to cage. The behavior exhibited in this video seems consistent with a shark merely going for a hang bait and subsequently bumping into the cage as a result.

As part of Georgina Harwood’s 100th birthday celebration, she went on a great white shark dive off Gansbai, South Africa, yesterday. In addition to the shark dive, Harwood also celebrated turning 100 with a skydive two days earlier. Harwood, a great-grandmother, began skydiving when she was 92, but this was her first shark dive.

Her recent skydive was done, in part, to help raise money to buy life-jackets for volunteers at South Africa’s National Sea Rescue Institute, according to a HuffPost UK article.

If you’d like to donate to Harwood’s life-jacket fundraiser, you can do so here.

The catch and release of a young great white shark (Carcharodon carcharias) off of a Florida beach near Panama City has been making headlines for the past few days. According to a photo on Dark Side Sharker’s Facebook page, fisherman Derrick Keeny landed the shark on March 1, 2015. The male white shark measured 9’8″ and is believed to be the first of its species to be landed from a beach in the Gulf of Mexico. The fisherman tagged the shark as part of the NOAA/NMFS Cooperative Tagging Plan and released it back into the ocean.

While the fishermen involved in the catch seemed to be well-intentioned with the tagging and release of the shark. Some shark researchers and conservationists called into question the legality of bringing the shark up onto the beach and posing for pictures, which is in violation of Florida’s protected species regulations, which specifically prohibit delaying the release of the shark for measurements and photos. It has yet to be reported whether the fishermen involved will be subjected to any legal repercussions.

The Australian Museum recently received a new intact goblin shark (Mitsukurina owstoni) specimen. The specimen is that of a young male and measures 1.26m in length. The shark was caught off Eden, New South Wales in water that was “several hundred meters deep.” This marks the fourth goblin shark in the museum’s Ichthyology Collection.

The goblin shark is a deep-water species that is rarely encountered by humans. It is known for its rather unconventional appearance, which includes pink skin, a flattened snout, and a jaw that can extend forward to capture prey. Adult goblin sharks are thought to typically reach lengths between 3-4m. Though, a specimen caught Gulf of Mexico in 2000 was estimated to be between 5.4 and 6.2m.

Great white sharks (Carcharodon carcharias) grow and reach sexual maturity at much slower rates than previously believed, according to a press release from NOAA Fisheries. A study completed in 2014 and published online last month in the journal of Marine & Freshwater Research used carbon-14 dating and vertebral band pair counts of 81 white shark specimens, collected in the western North Atlantic Ocean, to develop a growth curve for the species. According to the results, female white sharks reach sexual maturity at approximately 33 years of age, while males reach maturity at approximately 26 years. Additionally, the results of the study indicate that the life-span of white sharks could exceed 70 years, which places them among one of the longest living species of fish.

The latest findings on the growth rates and life-span of white sharks provides important information for conservation efforts of the species. Low reproduction rates coupled with slow growth and maturation rates could potentially put the species at greater risk for population decline, since losses in populations are not quickly replaced. Great white sharks are a protected species in U.S. waters and legally must be released live, if captured. However, individual white sharks are sometimes killed as a result of incidental by-catch from commercial fisheries, so it is important that these types of incidents be managed to protect the welfare of white shark populations, as a whole.

Samsung is promoting it’s head-mounted Gear VR display with some 360-degree footage of great white shark diving off Port Lincoln, Australia. Head-mounted displays like the Gear VR and Occulus Rift offer viewers an immersive experience that can simulate a completely different environment.

I shot some similar white shark footage using the Kolor Abyss 360 rig at Isla de Guadalupe, Mexico, last September. This footage should be compatible with both the Samsung Gear VR and Occulus. If you don’t have a head-mounted display, you can still take advantage of the 360-degree effect, using your mouse to click and drag to change the angle.

Stealthy seals use subsurface structures to sneak by white sharks

Predators are highly influential in ecosystems because of the many top-down effects they can have. The most obvious and direct way predators influence an ecosystem is by eating and reducing the number of prey animals in the system, but another equally important way is the indirect influence they have on the behaviour of prey animals.

If you have avoided parking on a risky-looking street, taken a different route between classes to avoid a bully, or abandoned a forest hike because of snapping twigs in the distance, you have been indirectly affected by perceived ‘predators’. In the wild, prey animals will also change their behaviour when they perceive that predators are around, and these altered behaviours often influence other species, ultimately shaping the ecosystem.

My research has focused on these same principles of predator/prey interactions in the ocean, and a great place to study oceanic predators and their prey are Cape fur seal colonies in South Africa. Every summer (November), Cape fur seals give birth to thousands of pups, and by winter (April – September) these ‘young-of-the-year’ seals begin to venture off their islands to swim offshore to the fishing grounds with the adults. These young-of-the-years are typically slow, plump from months of a mostly fat milk diet, and – most importantly – naïve. White sharks take advantage of this naivety and aggregate around seal colonies every winter. Young-of-the-year pups are forced to learn how to avoid sharks quickly or suffer some rather permanent consequences. This means that during a full year, every seal colony goes through a period of high white shark presence (winter) and very low to no white shark presence (summer). Therefore, we are able to study how seals act ‘normally’ during the summer when there are no/very few sharks and how they change their behaviour in the winter to avoid white sharks.

Also, there are many different kinds of seal colony islands along the coast, which lets us ask more questions about how seals use their environment to avoid sharks. I conducted my study at the Dyer Island/Geyser Rock system, which is home to ‘Shark Alley’ as well as many shallow reefs, kelp forests, and shipwrecks. About 100km to the east is another seal colony called Seal Island, which is a world-famous spot to see white sharks predate on seals, but this island system lacks the abundant nearby structures/reefs/kelp forests that are present at Geyser Rock. By looking at these two different kinds of islands, we can also examine how structures – or ‘refugia’ – may alter how seals avoid white sharks at Geyser Rock from how seals avoid white sharks at Seal Island.

Vimeo user Edwar Herreño recently added a video documenting six killer whales (Orcinus orca) hunting a tiger shark (Galeocerdo cuvier) off Cocos Island. The orcas appear to use a team effort to huntand appear and then drown the shark in the video. The video description says that the orcas fed on the shark after killing it.

Much like last year’s mockumentary “Megalodon: The Monster Shark Lives”, Discovery Channel’s first episode of this year’s Shark Week has come under fire for it’s fictional account of “Submarine,” a giant man-eating great white shark with roots in a South African urban legend. “Shark of Darkness: Wrath of Submarine” plays out like a documentary, though it’s actually just an account of fictional events, plagued with less-than-convincing acting and special effects, in the eyes of many viewers.

Twitter was lit up with disgruntled viewers on Sunday night when the episode premiered, and numerous online media outlets have since voiced their distaste in Discovery’s decision to peddle out another faux “documentary.”

In Discovery’s defense, the show did contain the following vague disclaimer.

Events have been dramatized, but many believe Submarine exists to this day.

While most viewers realized from the get-go that this is a piece of fiction, others bought into it as a real-life account of a ‘monster shark’ with an appetite for humans. “Submarine” was noted to have an “insatiable taste for human blood,” and had adapted methods to attack humans more efficiently.

Is this really the kind of message Discovery Channel should be sending its viewers about sharks?

You can check some other opinions about Shark of Darkness by following the links below.